[1] When the district was first established, it covered parts of the north and northwest suburbs of Cook County.
[2] New boundaries were adopted in August 2001, with redistricting taking place following the 2000 United States Census.
The district contained the entirety of both the Barrington and Palatine townships[4] The district, as redistricted in 2012 following the 2010 United States Census, included parts of Arlington Heights, Barrington, Buffalo Grove, Deerfield, Deer Park, Glencoe, Glenview, Golf, Hoffman Estates, Iverness, Mount Prospect, Northfield, Northbrook, Palatine, Prospect Heights, Rolling Meadows, Schaumburg, Wheeling, and Wilmette.
[12][13] In the 2016 United States presidential election, the Democratic ticket of Hillary Clinton and Tim Kaine won a strong victory in the district over the Republican ticket of Donald Trump and Mike Pence.
[13] The commissioner of the district flipped to the Democratic Party in 2018, a year which saw an overall strong performance by the Democratic Party in that year's elections in Illinois and an unprecedentedly strong and well-funded effort by the Cook County Democratic Party to target the district.